1. Field of the Invention
This invention relates to water filters and more particularly, to an underwater filtration system or operator which can be floated on a water body to filter and disinfect water from the water body for drinking or other purposes. The underwater filtration operator includes a typically split housing having a selected configuration and divided into multiple filtration units which receive water from the water body, each of which filtration units includes at least one, and preferably, two filter elements or medium, for filtering the water. A pump is provided in the housing for pumping the filtered water to a suitable container or dispenser or to a reverse-osmosis filtration unit for further filtration, and a positive electrical charge may be applied to the housing in conjunction with the introduction of forced air into a raw water chamber, to neutralize negatively charged impurities in the raw incoming water flowing through the filter media and improve filtration efficiency.
Treatment processes for filtering surface water have remained virtually unchanged for over half a century. Many surface water treatment plants utilize large settling basins, known as clarifiers, to settle out heavy solids from water prior to fine-screening the water, using rapid sand filters. Some of these treatment plants use a mixing chamber clarifier to separate the heavy solids from the water. Such a mixing chamber clarifier requires the introduction of polymers, lime, alum or other types of media into the water to be treated, which media bind particulate impurities in the water and fall with the bound impurities to the bottom of the mixing chamber. The filtered water, substantially devoid of the larger impurities, is then typically processed through horizontal sand filters which remove smaller impurities from the water. The sand filters must be periodically backwashed using large quantities of clean water because they repeatedly become clogged with the smaller particles that were not removed from the water during the clarification process. The fewer the particles removed during the clarification process, the more often the backwashing procedure must be repeated.
The foregoing types of surface water treatment plants are associated with many problems due to the nature of their operation. Numerous pumps and an expensive and elaborate intake structure must be installed in the water supplies to conduct the water to the plants for treatment. Another problem involves the disposal of solids that are removed from the water. Formerly, these solids, along with the chlorine, polymers, lime or other particulate binding media, were pumped back into the pre-filtered water from which they were removed. Due to recent environmental legislation, however, it is no longer lawful to discharge the particulate binding media into the pre-filtered water supply, as these materials are not endemic to the water that is being treated. Another problem associated with these filtration systems is that the polymers or other particle binding media introduced into the filtration system are harmful to certain types of boiler water industrial filtration equipment which utilizes reverse osmosis. This increases the cost of boiler water for industrial consumers. Furthermore, disinfectant chemicals introduced into the filtered water do not always kill all parasites found in water sources. Moreover, rapid sand filters cannot remove all of these parasites, some of which remain in the water and present a potentially dangerous health risk. Another problem associated with these surface water treatment plants is the inability to remove harmful chemicals which may contaminate the water supply by agricultural run-off or accidental spills. Accordingly, surface treatment plants can be costly and time-consuming to build and maintain.
A number of different types of filters are known in the art for filtering surface water. Patents of interest in this regard include U.S. Pat. No. 4,606,819, issued Aug. 19, 1986, to Colson; U.S. Pat. No. 4,643,836, issued Feb. 17, 1987, to Schmid; U.S. Pat. No. 4,657,672, issued Apr. 14, 1987, to Allen; U.S. Pat. No. 4,950,393, issued Aug. 21, 1990, to Goettl; U.S. Pat. No. 5,160,039, issued Nov. 3, 1992, to Colburn; U.S. Pat. No. 5,549,828, issued Aug. 27, 1996, to Ehrlich; arid U.S. Pat. No. 6,027,639, issued Feb. 22, 2000, to J. Lenhart et al. My U.S. Pat. No. 6,790,345, issued Sep. 14, 2004, details an underwater filtration operator for floating on a water body and producing clarified water from the water body.